diff --git a/schema/field.go b/schema/field.go
index 2e649d81..b49b7de6 100644
--- a/schema/field.go
+++ b/schema/field.go
@@ -201,7 +201,7 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 	case reflect.String:
 		field.DataType = String
 		isFunc := strings.Contains(field.DefaultValue, "(") &&
-			strings.Contains(field.DefaultValue, ")")
+			strings.Contains(field.DefaultValue, ")") || strings.ToLower(field.DefaultValue) == "null"
 
 		if field.HasDefaultValue && !isFunc {
 			field.DefaultValue = strings.Trim(field.DefaultValue, "'")
diff --git a/tests/default_value_test.go b/tests/default_value_test.go
index aa4a511a..44309eab 100644
--- a/tests/default_value_test.go
+++ b/tests/default_value_test.go
@@ -13,6 +13,7 @@ func TestDefaultValue(t *testing.T) {
 		Name    string `gorm:"not null;default:foo"`
 		Name2   string `gorm:"size:233;not null;default:'foo'"`
 		Name3   string `gorm:"size:233;not null;default:''"`
+		Name4   string `gorm:"size:233;default:null"`
 		Age     int    `gorm:"default:18"`
 		Enabled bool   `gorm:"default:true"`
 	}